274 J. T. CUNNINGHAM. 



cord on its inner side dorsally. The cords are entirely free 

 from the epidermis. The neural canals are similar in size and 

 appearance to those in Sigalion boa. 



Among the Terebellidae I find a median neural canal in 

 Lanice conchilega, Malmgren : it is of considerable size, 

 but has not such well-defined fibrous walls as are usually 

 present. In Amphitrite Johnstoni I have been unable to 

 detect any canal, nor in Terebellides Stroemi. 



In the Ampharetidae, however, which are, so to speak, on the 

 way towards the Terebellidae, the neural canals are large and 

 conspicuous, and have the typical structure. In Mel inn a 

 cristata there is one on the inner side of each nerve-cord in 

 the thoracic region. 



In the Capitellidse (Capitella and Notomastus) the nerve-cords 

 lie in the epidermis posteriorly, while in a few of the anterior 

 somites they are entirely separated from it by both the circular 

 and longitudinal muscles. In this anterior region there is a 

 large median neural canal on the dorsal side of the double cord 

 in Notomastus. In Capitella the canal is absent. 



Among the Maldanidae I have examined Nicomache lum- 

 bricalis and Axiothea catenata. In the former the nerve- 

 cords are not separated from the epidermis, and there is a 

 considerable single median neural canal above the cords in both 

 species. 



Among the Hermellidse, in Sabellaria, as pointed out by 

 Mcintosh, the two cords are at a considerable distance from one 

 another ; they are completely separated from the epidermis and 

 lie on the upper and inner side of the ventral longitudinal 

 muscles. Each has a large neural canal, similar to that of 

 Sabella, on its inner side (fig. 26). 



In Serpula the neural canals are similar in structure and 

 position to those of Sabella. 



Mcintosh mentions a small and indistinct neural canal in 

 Ammotrypane aulogaster, H. R. In some of my sections 

 it can be made out, but always with difficulty, as it is exceed- 

 ingly ill-defined. In Cirratulus cirratus, also, neural 

 canals are absent. 



